With the increased regulation on the vehicle safety, more and more vehicles are equipped with curtain airbags to reduce injuries to passengers during a vehicle side impact collision. A curtain airbag is typically folded between a headliner and a roof sheet metal at an uninflated state, and will break through a coupling between the headliner and a side trim of the vehicle and then be deployed along a predetermined passage when inflated upon the side impact collision of the vehicle. Because the deployment of curtain airbag deforms an edge of the headliner, the design of headliner influences the deployment of the curtain airbag. Various approaches have been developed to improve the deployment of the curtain airbags. For example, U.S. Pat. No. 6,142,506 discloses an energy absorbing vehicle trim and an airbag. The trim piece is spaceably mounted to the energy absorbing member and cooperative therewith to move from a covering position covering the inflatable restraint in an uninflated state to a deployed position so as to partially deflect from the vehicle body structure to allow the inflatable restraint to inflate along the surfaces adjacent the vehicle body structure. In another example, U.S. Pat. No. 8,876,152 discloses an inflatable restraint assembly including a guide ramp. At least a portion of the inflatable curtain portion of the curtain airbag module extends along the guide ramp when the inflatable curtain portion is in the deployed configuration.